Comment 1 for bug 1513849

calibre uses an "atomic update" technique to ensure the file it is
editing to is never corrupted in the event of crashes/power failure in
the middle of saving. Part of that technique requires the original file
to exist. I suppose I could look into trying to handle the case of the
original file going missing during an editing session, but, I dont know
if that will be feasible or not, if not, trying to handle the case of
the original file being deleted in the middle of an editing session is
not worth the tradeoff.